code: def preprocess_list(x: List[np.ndarray]) -> np.ndarray:
      if (
          len(x) > 1
      ):  # test List[Any] reference data inputs to the detector with Any=np.ndarray
          return np.concatenate(x, axis=0)
      else:  # test Any inputs to the prediction function of the detector with Any=List[np.ndarray]
          return np.array(x)[0]
  
file_path: alibi-detect/alibi_detect/cd/pytorch/tests/test_mmd_online_pt.py
imports: from functools import partial
  from itertools import product
  import numpy
  import pytest
  import torch
  import torch.nn
  from typing import Callable, List
  from alibi_detect.cd.pytorch.mmd_online import MMDDriftOnlineTorch
  from alibi_detect.cd.pytorch.preprocess import HiddenOutput, preprocess_drift
  from alibi_detect.utils._random import fixed_seed
label_desc: Use image node_id 1 for calling a global function with example usage: preprocess_list(x) and returns: np, np